chore: add README.md to class-hash

crates/class-hash/README.md

@@ -0,0 +1,8 @@
+# pathfinder-class-hash
+
+[![Documentation](https://docs.rs/pathfinder-class-hash/badge.svg)](https://docs.rs/pathfinder-class-hash)
+[![Crates.io](https://img.shields.io/crates/v/pathfinder-class-hash)](https://crates.io/crates/pathfinder-class-hash)
+[![License](https://img.shields.io/crates/l/pathfinder-class-hash)](https://github.com/eqlabs/pathfinder/blob/main/crates/class-hash/LICENSE)
+
+
+This crate provides functionality to compute class hashes for both Cairo 0.x and Sierra (Cairo 1.x+) contracts in the Starknet ecosystem. It implements the official Starknet class hash computation algorithm, handling special cases for different Cairo versions and maintaining compatibility with the network's expectations.